Suppressing Trade Barriers. This enables them increase the competitive position of their businesses. The EU has a common external tariff (CET) which means that all member countries levy import duties on imports.Barriers to international trade – tariffs and trading blocsAlliances help countries discover new markets and technologies. Trade creation and diversion. In some cases, this abolition of internal barriers to trade is replaced with a common external tariff against non-members of the RTA.Trading Blocs. The Development of Trading Blocs Also known as a regional trade agreement (RTAs), a trading bloc is essentially a group of countries that remove tariffs and quotas on trade between themselves.